264 MYCOLOGY 



eludes the fungi which c§iuse the leaf spot of the pear, Septoria pyricola, 

 the late blight of the celery S. petroselini (Figs. 105 and 106), the leaf 

 blight of the tomato S. lycopersici and the leaf spot of currants, S. rihis. 

 The pycnidia in this genus develop under the epidermis of the host 

 producing leaf spots. The center of the leaf spot is occupied by the pore 

 of the spheric, black pycnidium. Leptothyrium pomi is an imperfect 

 fungus responsible for the sooty blotch of the apple and other 

 plants. According to Floyd the same fungus causes the fly speck of 

 apples. The genus Entomosporium is a small one with closed half- 

 spheric, black pycnidia. The spores suggest an insect in being four- 

 celled, the cells being arranged cross-like with attenuated extremities 

 and swollen bases. Entomosporium maculatum is the cause of the leaf 

 blight of the pear and quince. 



II. MELANCONIALES.^ — The mycelium is formed in the interior 

 of the host plants. The fruit is in the form of a conidial hymenium, 

 which is produced below the epidermis of the host, breaking through 

 clefts in the surface of the host as bright or black spots. The conidio- 

 phores stand closely together and are simple, or rarely branched, hya- 

 line, or rarely dark-colored. Pycnidia are unknown in this group of 

 imperfect fungi. The spores are of different shapes, single or in chains. 

 The order includes both parasites and saprophytes. The pustule, or 

 acervulus, which produces spores in Gleosporium may be extensive 

 The short conidiophore arise from or are inclosed within a cushion, 

 or stroma, of fungous tissue. The rupture of the epidermis of the host 

 is accomplished by the opening of the stroma. The ovoidal, fusiform, 

 slightly curved hyahne spores are discharged with the opening of the 

 stroma. Some species of Gloeosporium are connected with other genera, 

 viz., Glomerella (rufomaculans) , Gnomonia and Pseud opeziza the im- 

 perfect stages of which were placed as species under the form genus 

 Glososporium, which is the important form pathologically speaking. 

 As examples of the form genus Gloeosporium, we have G. ampelophagum 

 which causes the anthracnose of the grape; G. venetum which is re- 

 sponsible for the anthracnose of blackberry and raspberry, while other 

 species attack the linden, walnut, pine and Norway maple. 



In Colletotrichum (Fig. 107) the conidial cushions have a bristly 

 border, while the conidiospores are in chains. Colletotrichum Lindemuth- 

 ianum causes anthracnose of bean, an important disease in gardens and 

 fields (Fig. 107). The cotton is attacked by C. gossypii, citrus fruits by 



